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J Appl Physiol 107: 1138-1143, 2009. First published August 6, 2009; doi:10.1152/japplphysiol.00149.2009
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Myoglobin concentration in skeletal muscle fibers of chronic heart failure patients

Martijn A. Bekedam,1,2 Brechje J. van Beek-Harmsen,2 Willem van Mechelen,3 Anco Boonstra,4 and Willem J. van der Laarse2

1Departments of Cardiology, ; 2Physiology, and ; 4Pulmonology, Institute for Cardiovascular Research and ; 3Department of Public and Occupational Health and EMGO Institute, VU University Medical Center, Amsterdam, The Netherlands

Submitted 11 February 2009 ; accepted in final form 4 August 2009

The purpose of this study was to determine the myoglobin concentration in skeletal muscle fibers of chronic heart failure (CHF) patients and to calculate the effect of myoglobin on oxygen buffering and facilitated diffusion. Myoglobin concentration, succinate dehydrogenase (SDH) activity, and cross-sectional area of individual muscle fibers from the vastus lateralis of five control and nine CHF patients were determined using calibrated histochemistry. CHF patients compared with control subjects were similar with respect to myoglobin concentration: type I fibers 0.69 ± 0.11 mM (mean ± SD), type II fibers 0.52 ± 0.07 mM in CHF vs. type I fibers 0.70 ± 0.09 mM, type II fibers 0.49 ± 0.07 mM in control, whereas SDH activity was significantly lower in CHF in both fiber types (P < 0.01). The myoglobin concentration in type I fibers was higher than in type II fibers (P < 0.01). Consequently, the oxygen buffering capacity, calculated from myoglobin concentration/SDH activity was increased in CHF: type I fibers 11.4 ± 2.1 s, type II fibers 13.6 ± 3.9 s in CHF vs. type I fibers 7.8 ± 0.9 s, type II fibers 7.5 ± 1.0 s in control, all P < 0.01). The calculated extracellular oxygen tension required to prevent core anoxia (PO2crit) in muscle fibers was similar when controls were compared with patients in type I fibers 10.3 ± 0.9 Torr in CHF and 11.5 ± 3.3 Torr in control, but was lower in type II fibers of patients 6.1 ± 2.8 Torr in CHF and 14.7 ± 6.2 Torr in control, P < 0.01. The lower PO2crit of type II fibers may facilitate oxygen extraction from capillaries. Reduced exercise tolerance in CHF is not due to myoglobin deficiency.

succinate dehydrogenase; critical oxygen tension; muscle fiber types; human


Address for reprint requests and other correspondence: W. J. van der Laarse, Dept. of Physiology, Van der Boechorststraat 7, 1081 BT, Amsterdam, The Netherlands (e-mail: wj.vanderlaarse{at}vumc.nl).






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